Vanillin cross-linked polyvinyl alcohol chitosan active packaging film as well as preparation method and application thereof

Abstract

The invention provides a vanillin cross-linked polyvinyl alcohol chitosan active packaging film as well as a preparation method and application thereof, and belongs to the technical field of film composite materials. The preparation method of the film comprises the following steps: dissolving chitosan in an acetic acid aqueous solution, and stirring at a constant temperature to obtain a solution A; dissolving polyvinyl alcohol in deionized water, and stirring at a constant temperature to obtain a solution B; uniformly mixing the solution A and the solution B, adding vanillin, and stirring at a constant temperature to obtain a solution C; uniformly mixing the solution C, a plasticizer and an anthocyanin solution to obtain a film forming solution; and defoaming the film-forming solution and preparing into a film to obtain the vanillin crosslinked polyvinyl alcohol chitosan active packaging film. The packaging film can show better tightness and hydrophobicity and lower water content and water vapor permeability, and meanwhile, the film has excellent oxidation resistance, so that foods such as fruits and vegetables, meat and cooked food have longer fresh-keeping time.

Description

Technical Field

[0001] The invention belongs to the technical field of film composite materials, and in particular to a vanillin cross-linked polyvinyl alcohol chitosan active packaging film, a preparation method and application thereof. Background Art

[0002] Food packaging mostly uses traditional plastic packaging, which has been widely used in the food packaging industry due to its wide variety, low price and stable properties. However, in actual application, it has also brought a series of problems in terms of environmental protection, human health, resource utilization, etc.

[0003] In food preservation, if fruits and vegetables are stored for too long, their cells will age, their nutrients will degrade, the nitrite in vegetables will increase, and their tissues will separate; the oxidation of fats in food will produce malondialdehyde (MDA), which will damage the human enzyme system and have carcinogenic toxicity. Fish products will not only lose color, aroma, and nutritional value due to fat oxidation, but also produce harmful substances such as valeraldehyde, hexanal, 4-hydroxynonanal, and malondialdehyde, which will give off a bad smell.

[0004] At present, cling film is very common in daily life, mainly used to keep food fresh and extend the shelf life of food. However, due to its composition, the thermal stability and antioxidant properties of cling film are greatly limited. Especially for different food categories, meat and vegetables need to use cling film with different properties.

[0005] Therefore, there is an urgent need for a fresh-keeping film with good anti-oxidation effect and which can be used for preserving various types of food. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a method for preparing a vanillin cross-linked polyvinyl alcohol chitosan active packaging film, which can show better tightness and hydrophobicity, lower water content and water vapor permeability. At the same time, the film has excellent antioxidant properties and can make fruits, vegetables, meat, cooked food and other foods have a longer shelf life.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a vanillin cross-linked polyvinyl alcohol chitosan active packaging film, comprising the following steps:

[0009] S1. Dissolve chitosan in an aqueous acetic acid solution and stir at a constant temperature to obtain a solution A;

[0010] S2. dissolving polyvinyl alcohol in deionized water with constant temperature stirring to obtain solution B;

[0011] S3. After mixing solution A and solution B evenly, add vanillin and stir at constant temperature to obtain solution C;

[0012] S4. Mixing solution C, plasticizer, and anthocyanin solution to obtain a film-forming solution;

[0013] S5. Defoaming the film-forming solution and forming it into a film to obtain a vanillin cross-linked polyvinyl alcohol chitosan active packaging film.

[0014] Preferably, the mass volume ratio of chitosan to acetic acid aqueous solution in S1 is 1 g:100 mL;

[0015] The volume concentration of the acetic acid aqueous solution is 1%.

[0016] The temperature of the constant temperature stirring is 50° C. and the time is 1 hour.

[0017] Preferably, the mass volume ratio of the polyvinyl alcohol to the ionized water in S2 is 3g:100mL.

[0018] The temperature of the constant temperature stirring is 95° C. and the time is 1 hour.

[0019] Preferably, the volume mass ratio of solution A, solution B and vanillin in S3 is: 100 mL: 100 mL: 3 g.

[0020] The temperature of the constant temperature stirring is 70° C. and the time is 0.5 h.

[0021] Preferably, the volume ratio of solution C, plasticizer, and anthocyanin solution in S4 is 100 mL: 3 mL: 1 mL;

[0022] The anthocyanin solution is prepared by mixing anthocyanin and deionized water in a volume ratio of 0.1:100.

[0023] Preferably, the plasticizer is glycerol.

[0024] Preferably, the mixing temperature in S4 is 40°C.

[0025] In a second aspect, the present invention provides a vanillin cross-linked polyvinyl alcohol chitosan active packaging film, which is prepared by the above-mentioned preparation method.

[0026] In a third aspect, the present invention provides the use of vanillin cross-linked polyvinyl alcohol chitosan active packaging film in food preservation.

[0027] In a fourth aspect, the present invention provides the use of vanillin cross-linked polyvinyl alcohol chitosan active packaging film in food anti-oxidation.

[0028] Contains at least the following beneficial technical effects:

[0029] (1) The film obtained by the present invention can show better tightness and hydrophobicity, lower water content and water vapor permeability, and the film has excellent antioxidant properties, which can make fruits, vegetables, meat, cooked food and other foods have a longer shelf life. Since a large number of phenolic hydroxyl groups on the surface of vanillin reduce or inhibit free radicals by transferring hydrogen atoms, the free radical scavenging ability is improved.

[0030] (2) The preparation method of the film obtained by the present invention is simple, the raw material source is wide, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a physical picture of the vanillin cross-linked polyvinyl alcohol chitosan active packaging film prepared in Example 1. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The "room temperature" and "normal temperature" mentioned in the present invention are all calculated as 25±2°C unless otherwise specified.

[0038] The raw materials and instruments used in the following examples of the present invention are commercially available unless otherwise specified.

[0039] Example 1

[0040] This embodiment provides a method for preparing a vanillin cross-linked polyvinyl alcohol chitosan active packaging film, comprising the following steps:

[0041] S1. Dissolve 1 g of chitosan in 100 mL of 1 v / v% acetic acid aqueous solution and stir at 70°C for 30 min to obtain solution A;

[0042] S2. Dissolve 3 g of polyvinyl alcohol in 100 mL of deionized water and stir at 95 ° C for 1 h to obtain solution B;

[0043] S3. After mixing solution A and solution B evenly, vanillin was added and stirred at 70°C for 0.5h to obtain solution C; wherein the volume mass ratio of solution A, solution B, and vanillin is: 100mL:100mL:3g;

[0044] S4. Solution C, glycerol, and anthocyanin solution 1 are mixed uniformly at a volume ratio of 100 mL:3 mL:1 mL at 40° C. to obtain a film-forming solution; wherein the anthocyanin solution is prepared by mixing anthocyanin and deionized water at a volume ratio of 0.1:100.

[0045] Comparative Example 1

[0046] This comparative example provides a packaging film, which is prepared in the same manner as in Example 1, except that the volume mass ratio of solution A, solution B, and vanillin in S3 is 100 mL: 100 mL: 0 g.

[0047] Comparative Example 2

[0048] This comparative example provides a packaging film, which is prepared in the same manner as in Example 1, except that the volume mass ratio of solution A, solution B, and vanillin in S3 is 100 mL: 100 mL: 1 g.

[0049] Comparative Example 3

[0050] This comparative example provides a packaging film, which is prepared in the same manner as in Example 1, except that the volume mass ratio of solution A, solution B, and vanillin in S3 is 100 mL: 100 mL: 5 g.

[0051] Experimental Example 1

[0052] The antioxidant effect of the film was determined using a DPPH free radical scavenging kit, see Table 1.

[0053] Table 1

[0054] Free radical scavenging rate% Example 1 93.28 Comparative Example 1 89.28 Comparative Example 2 91.31 Comparative Example 3 94.76

[0055] The larger the free radical scavenging rate data, the better the antioxidant performance of the film. According to the experimental results, as the concentration of the cross-linking agent vanillin increases, the ability to scavenge free radicals increases, and the antioxidant capacity of the film gradually increases, indicating that vanillin has a positive effect on the antioxidant capacity of the film.

[0056] Experimental Example 2

[0057] The thickness and mechanical properties of the active films were tested, see Table 2.

[0058] Table 2

[0059] thickness Tensile Strength Elongation at break Example 1 <![CDATA[0.15±0.012 a ]]> <![CDATA[19.91±2.99 c ]]> <![CDATA[489.25±82.04 c ]]> Comparative Example 1 <![CDATA[0.15±0.021 a ]]> <![CDATA[22.25±2.27 a ]]> <![CDATA[597.19±75.02 a ]]> Comparative Example 2 <![CDATA[0.20±0.032 b ]]> <![CDATA[17.98±2.25 b ]]> <![CDATA[453.34±68.20 b <!-- 3 -->]]> Comparative Example 3 <![CDATA[0.12±0.031 c ]]> <![CDATA[20.18±4.23 d ]]> <![CDATA[398.14±118.70 d ]]>

[0060] By testing the thickness and mechanical properties of the active film, it was found that the addition of vanillin can reduce the tensile strength and elongation at break of the active film. Studies have shown that the thickness of the film depends on the solid content and preparation conditions of the film components. The thickness of the cling film is not significantly affected by the concentration of vanillin, but the elongation at break is significantly reduced, indicating that the addition of vanillin reduces the fluidity of the film matrix and restricts the movement of macromolecules in the film matrix. This may be due to the uniform network structure formed by the addition of vanillin in the active film.

[0061] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a vanillin cross-linked polyvinyl alcohol chitosan active packaging film, characterized in that: The following steps are involved: S1. Dissolve chitosan in an aqueous acetic acid solution and stir at a constant temperature to obtain a solution A; S2. dissolving polyvinyl alcohol in deionized water with constant temperature stirring to obtain solution B; S3. After mixing solution A and solution B evenly, add vanillin and stir at constant temperature to obtain solution C; S4. Mixing solution C, plasticizer, and anthocyanin solution to obtain a film-forming solution; S5. Defoaming the film-forming solution and forming it into a film to obtain a vanillin cross-linked polyvinyl alcohol chitosan active packaging film.

2. The method according to claim 1, characterized in that The mass volume ratio of chitosan to acetic acid aqueous solution in S1 is 1 g:100 mL; The volume concentration of the acetic acid aqueous solution is 1%; The temperature of the constant temperature stirring is 50° C. and the time is 1 hour.

3. The method according to claim 1, characterized in that The mass volume ratio of polyvinyl alcohol to ionized water in S2 is 3 g:100 mL; The temperature of the constant temperature stirring is 95° C. and the time is 1 hour.

4. The method according to claim 1, characterized in that The volume mass ratio of solution A, solution B and vanillin in S3 is: 100 mL: 100 mL: 3 g; The temperature of the constant temperature stirring is 70° C. and the time is 0.5 h.

5. The method according to claim 1, characterized in that: The volume ratio of solution C, plasticizer, and anthocyanin solution in S4 is 100 mL: 3 mL: 1 mL; The anthocyanin solution is prepared by mixing anthocyanin and deionized water in a volume ratio of 0.1:

100.

6. The method according to claim 5, characterized in that The plasticizer is glycerol.

7. The method according to claim 1, characterized in that The mixing temperature described in S4 is 40°C.

8. A vanillin cross-linked polyvinyl alcohol chitosan active packaging film, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the vanillin cross-linked polyvinyl alcohol chitosan active packaging film according to claim 8 in food preservation.

10. Use of the vanillin cross-linked polyvinyl alcohol chitosan active packaging film according to claim 8 in food anti-oxidation.

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